Comparative electromagnetic shielding performance of Ti ₃ C ₂ T _<i>x</i> -PVA composites in various structural forms: compact films, hydrogels, and aerogels

Abstract

The structural design of light-weight MXene-polymer composites has attracted significant interest for enhancing both electromagnetic interference (EMI) shielding performance and mechanical strength, which are critical for practical applications. However, a systematic understanding of how various structural configurations of MXene composites affect EMI shielding is lacking. In this study, light-weight Ti₃C₂T_<i>x</i>-PVA composites were fabricated in three structural forms, hydrogel, aerogel, and compact film, while varying the Ti₃C₂T_<i>x</i> areal density (14 to 20 mg cm^-2) to elucidate the role of structural design in X-band EMI shielding and mechanical properties. The EMI shielding performance depends on the structural configuration and areal density of the MXene in Ti₃C₂T_<i>x</i>-PVA composites. The shielding effectiveness increases with increasing Ti₃C₂T_<i>x</i> content in each configuration. At a fixed Ti₃C₂T_<i>x</i> areal density of 0.02 g cm^-2, the Ti₃C₂T_<i>x</i>-PVA hydrogel demonstrated the highest shielding effectiveness (SE = 70 dB at 10 GHz), attributed to strong dipole polarization and efficient ionic conduction behavior, followed by the compact film (40 dB) and then the aerogel (21 dB). Notably, the aerogel achieved the highest absorption coefficient (<i>A</i> = 0.89) due to the improved impedance matching and pronounced internal reflections, whereas the hydrogel and compact film exhibited reflection-dominated shielding. Furthermore, the incorporation of PVA polymer molecules into Ti₃C₂T_<i>x</i> MXenes significantly enhanced their mechanical properties across all configurations: the hydrogel achieved high stretchability (636%), the aerogel displayed superior compressive strength (0.215 MPa), and the compact film reached a tensile strength of 56 MPa, each surpassing the performance of its pristine Ti₃C₂T_<i>x</i> MXene counterpart. Overall, tailoring the structural configuration into a hydrogel, aerogel, or compact film offers versatile routes for optimizing both EMI attenuation and mechanical performance of MXene-polymer composites.